Cast reactive metal body

ABSTRACT

A cast reactive metal body that can be used as weapon cases is offered. It is cast with aluminum or aluminum alloys with small particles and/or fibers of metals of high density such as molybdenum, tungsten or hafnium. Aluminum alloys are those that can get easily ignited when heated and burn fast afterwards in particulate forms. Metals that react intermetallically with aluminum are excluded. The particles and fibers are of the size between a few microns and a few hundreds of microns in diameter. The length of the fibers is longer than the diameter. The weight percentage of aluminum and/or aluminum alloys range from 10 to 90 percent and the weight percentage of heavy metal particles/fibers ranges from 90 to 10 percent. Other inert materials such as ceramic particles can be added in small amounts.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a new class of materials, called reactive materials or reactive material structures. These materials are inert in standard atmospheric conditions, but as they are used as weapon cases housing high explosives, when these high explosives detonate, they generate fine fuel particles such as aluminum or aluminum alloy particles. These fuel particles are sufficiently heated during the case expansion and breakup in such a way that they react with air immediately surrounding the weapon. This reaction with air enhances the blast strength of the weapon beyond that of the high explosives alone. In many situations, it would be beneficial to replace steel cases that are currently used in weapons with these new materials in order to enhance the blast power of the weapon.

2. Description of the Related Art

Three conditions need to be satisfied for the reactive materials to become good candidates for weapon cases. First, they have to break and generate fine fuel particles when they are subjected to a detonation of high explosives next to them (friability condition). Second, the fuel particles must have been heated to a high enough temperature so that when they become in contact with the surrounding air, they start burning immediately and fast (reactability condition). Once the above two conditions are met, enhanced blasts can be generated. However, the above two conditions are not enough themselves for the reactive materials to be used as weapon cases. The third condition is that they would have strong enough material properties to allow them to house the high explosives, to be handled and stored safely, to be fired upon command, and in some cases to penetrate certain targets and then to function as intended (material properties condition).

Although each of the three above mentioned requirements (friability, reactability with air, and material properties) can be easily satisfied independently by various methods, manufacture of reactive materials that satisfy all three requirements together has been challenging.

New materials are currently being developed by several government and industrial laboratories in small scales and they show promise of satisfying all three requirements. However, their methods of manufacturing is extremely time consuming and expensive. It will be challenging to mass produce these laboratory type research materials and use them as weapon cases.

This invention provides an answer to satisfy all of the above three requirements and to keep the manufacturing cost well below those of the current research materials.

DESCRIPTION OF THE INVENTION

The invention takes advantage of several observations. First, it is observed that particles of aluminum or aluminum alloys such as magnesium-aluminum alloys are easily ignited and burn fast at lower temperatures than most other metal particles. It is also observed that aluminum and magnesium releases very large heat of combustion. For aluminum, the heat of combustion is around 7400 cal/g and for magnesium it is around 6200 cal/g. In contrast, the detonation energy of TNT, a most common explosive, releases only about 1000 cal/g.

Second, it is observed that aluminum particles of the size of tens of microns ignite and burn within a few milliseconds or less. It is within the time limit of releasing and depositing the reaction energy into expanding blast waves such that the strength of the blast itself can be enhanced.

Third, it has been observed that aluminum or aluminum alloy particles mixed and pressed with high density metal particles can break into fine particles and can get heated to high enough temperatures for reaction initiation when subjected to a strong shock. The process is called shock-induced micromechanical deformation. Essentially, the aluminum or aluminum alloys will move around the high density metal particles when they are pushed by a shock. These fuel metals will undergo plastic deformation, and get heated. If the plastic deformation is large enough, it can cause the fuel metal to break into fine particles with sufficient heating of these particles. It has been shown that the size of these fuel particles depend, in some cases, upon the size of the high density metal particles originally mixed in with the fuel.

Fourth, the micromechanical plastic deformation may be enhanced further when mixed in with fibers, rather than particles, of high density metals, and at the same time, may enhance overall bulk mechanical strengths of these reactive material structures. On the other hand, mixing process becomes easier with the inclusion of high density particles to the fibers, especially at high weight percentages of high density metals. The micromechanical deformation can be further enhanced by the presence of small amounts of hard particles such as ceramic particles.

The invention would cast, into a mold, aluminum or aluminum alloys with high density metal fibers and/or particles at desirable weight percentages at below the melting temperature of high density metals so that structural integrity of those high density metal particles and fibers are not degraded by high temperatures.

BRIEF DESCRIPTION OF THE DRAWINGS

There are no drawings for this invention. 

1-2. (canceled)
 3. A cast reactive metal body for use in weapon casings, comprising: A reactive metal matrix, comprising between 10% and 90% of the cast reactive metal body weight; High-density metal constituents embedded within the cast reactive metal matrix; the high-density metal constituents do not react inter-metallically with the cast reactive metal matrix; the high-density metal constituents comprising between 10% and 90% of the cast reactive metal body weight; the high-density metal constituents have a diameter between a few microns and a few hundreds of microns; and Small hard inert filler materials embedded within the reactive metal matrix; the small hard inert filler materials do not melt at or near the melting point of said reactive metal matrix; the small hard inert filler materials comprising between 0% and 30% of the cast reactive metal body weight; the hard inert filler materials have a diameter 2-10 times smaller than those of the high density metal components;
 4. The cast reactive metal body of claim 3, wherein the cast reactive metal matrix is aluminum.
 5. The cast reactive metal body of claim 3, wherein the cast reactive metal matrix is an aluminum alloy.
 6. The cast reactive metal body of claim 5, wherein the aluminum alloy is an aluminum-magnesium alloy.
 7. The cast reactive metal body of claim 3, wherein the cast reactive metal matrix can be easily ignited when heated and burns quickly with air when in particulate form.
 8. The cast reactive metal body of claim 3, wherein high density metals used for the high-density metal constituents embedded within the reactive metal matrix are selected from the group consisting of molybdenum, tungsten or hafnium.
 9. The cast reactive metal body of claim 3, wherein the high-density metal constituents are particles.
 10. The cast reactive metal body of claim 3, wherein the high-density metal constituents are fibers.
 11. The cast reactive metal body of claim 12, wherein the fibers have length longer than their diameter.
 12. The cast reactive metal body of claim 3, wherein the high density metal constituents are metal wools.
 13. The cast reactive metal body of claim 3, wherein the high density metal constituents are a combination of particles, fibers, and metal wools.
 14. The cast reactive metal body of claim 3, wherein the hard inert filler materials are selected from the group consisting of metal oxide particles (ceramic particles) of various sizes.
 15. A method for producing a weapon casing comprising: Mixing high-density metal constituents and small hard inert filler materials with a liquid reactive metal to form a mixture of said high-density constituents, hard filler materials and liquid reactive metal of desired weight proportions; Pouring said mixture to form a weapon casing; Wherein said reactive metal does not react intermetalically with the high-density metal constituents; and Wherein said weapon casing can form particles that are easily ignited when heated and burn quickly with air when a high explosive placed next to the said weapon casing is detonated.
 16. A method for producing a weapon casing comprising: Mixing high-density metal constituents and small hard inert filler materials with enough liquid reactive metal to form a mixture of said high-density constituents, excess hard filler materials beyond desired weight proportions and excess reactive metal beyond desired weight proportions; Pouring said mixture into a mold; Covering the mold with a porous barrier through which the liquid reactive metal and hard inert filler materials can flow but said high-density metal constituents cannot; Squeezing liquid reactive metal in excess of the desired amount and excess hard filler materials out to form a weapon casing of desired weight proportion between the heavy-metal constituents, hard inert filler materials and the liquid reactive metal; Wherein said reactive metal does not react intermetalically with the high-density metal constituents; and Wherein said weapon casing can form particles that are easily ignited when heated and burn quickly with air when a high explosive placed next to the said weapon casing is detonated.
 17. A method for producing a weapon casing comprising: Placing heavy metal constituents (in fiber or wool forms) into a mold of weapon casing; Rearranging the heavy-metal constituents to partially but not completely fill the mold; Mixing a liquid reactive metal with hard inert filler materials to form a mixture of the liquid reactive metal and the hard inert filler materials; Pouring the mixture of liquid reactive metal and hard inert filler materials into the said mold with the heavy-metal constituents already in the mold to form a weapons casing, Wherein the pouring causes the liquid reactive metal, hard inert filler materials, and heavy-metal constituents to be mixed to desired weight proportions; Wherein said reactive metal does not react intermetalically with the high-density metal constituents; and Wherein said weapon casing can form particles that are easily ignited when heated and burn quickly with air when a high explosive placed next to the said weapon casing detonated.
 18. A method for producing a weapon casing comprising: Placing heavy metal constituents into a mold of weapon casing; Rearranging the heavy-metal constituents to fill the mold; Mixing a liquid reactive metal with hard inert filler materials to form a mixture of said liquid reactive metal and hard inert filler materials; Pouring enough of the mixture into the mold; Wherein the pouring causes the liquid reactive metal, the hard inert filler materials, and the heavy-metal constituents to be mixed; Covering the mold with a porous barrier through which the liquid reactive metal and hard inert filler materials can flow but the high-density metal constituents cannot; Squeezing any excess the liquid reactive metal and hard inert filler materials out to form a weapon casing of desired weight proportion between the heavy-metal constituents, the hard inert filler materials and the liquid reactive metal; Wherein said reactive metal does not react intermetalically with the high-density metal constituents; and Wherein the weapon casing can form particles that are easily ignited when heated and burn quickly with air when a high explosive placed next to the weapon casing is detonated.
 19. The method of claim 18, where the heavy-metal constituents used are fibers.
 20. The method of claim 18, where the heavy-metal constituents used are metal wools. 